Area of an Inner Rectangle

Date: 01/19/2003 at 17:00:43
From: Jamie
Subject: Word problem...
When Fred and Wilma reached retirement, they were finally able to buy
the house of their dreams. It had a 40 ft by 72 ft rectangular yard.
Wilma cultivated 5/12 of the area in flowers, which she grew in an
even border around the central grass area. Every morning Fred walked
Dino around the central grass area inside the flowers. How many laps
did he have to do to walk at least 1/4 mile?
I don't understand where to start because I can't visualize what facts
are essential in arriving the answer. Is it really important that
Wilma cultivated 5/12 of the yard in flowers? Or should I begin with
how many feet are in a mile?
How would you even determine 5/12 of a 40 ft by 72 ft rectangular
yard? Is the central grass area that Fred walks Dino around the entire
yard? Or just the remaining fraction? Please help!